Here's a little guide on how to convert your osu! skins to Hexis themes. Please note that Hexis doesn't yet support all of the features that osu! skins have, but this guide will help you in making a skin that looks as close as your osu! skin as possible.

Create a new folder in Program Files (x86)\Hexis\data\themes and name it whatever you want your theme's folder to be namedCopy the following files directly from the osu skin's folder to your new empty folder (not all skins will have all of them, if some are missing just ignore them):

Hitcircle numbers (object-1, 2, 3...) must be scaled down to about 74% of their original size. I use CTRL + R in Paint.NET for this.

Make a copy of hitcircleoverlay.png in your folder and rename it to holdcircleoverlay.png, then edit it to make it look whatever you want your hold circles to look like. I usually add black stripes to the overlay (like this: http://a.pomf.se/yrlkjf.png).Create a followpoint.png file in your folder and create your follow points if you want. Keep in mind that Hexis doesn't support osu!-like directional follow points yet, so you're stuck to a single image for follow points, which means that you will have to use stuff like dots instead of arrows or lines.

Create a theme.xml in your folder and paste the following in it (make sure to edit it to match the skin.ini settings of the osu skin you're converting):

Examples of converting some skin.ini settings to theme.xml settings (note that these must be placed between <theme version="1.0"> and </theme>).If you don't know how to convert colors to hex like I did in the examples, just use rgb values like this: r="255" g="0" b="0" or use this converter http://www.javascripter.net/faq/rgbtohex.htm.